Czech government recently launched new service for delivering letters. The service is working only on MS-Windows, however WS access is provided. I have created simple application that can work with that, but several modifications to nusoap were necessary. Please consider including them in your package: http://martin.hinner.info/schranky/nusoap/lib/nusoap.php.txt
(three important changes: introduced maxtries variable to increase non-200 retry count, implemented automatic cookie acceptance and I have also uncommented code to use ssl socket for https - this should be handled using some variable to force socket mode, not curl).
Also nusoap is not able to load wsdl files from http://www.czebox.cz/static/pages/dokumentace.zip (there is a lot of Czech documents, but also wsdl files). Problem is with this include tag:
<xs:include schemaLocation="dmBaseTypes.xsd" />
I have temporarily fixed this by manually inserting this file. This should be fixed.